1. Field of Invention
The present invention is directed to methods of preparing a cased wellbore for stimulation operations and, in particular, to interventionless methods for preparing the cased wellbore for stimulation operations using pressure actuated sleeves and apparatuses for temporarily restricting fluid flow through the wellbore casing to prepare the wellbore casing for stimulation operations as opposed to using additional wellbore intervention methods such as tubing conveyed perforation.
2. Description of Art
Ball seats are generally known in the art. For example, typical ball seats have a bore or passageway that is restricted by a seat. The ball or plug element is disposed on the seat, preventing or restricting fluid from flowing through the bore of the ball seat and, thus, isolating the tubing or conduit section in which the ball seat is disposed. As force is applied to the ball or plug element, the conduit can be pressurized for tubing testing or tool actuation or manipulation, such as in setting a packer. Ball seats are used in cased hole completions, liner hangers, flow diverters, fracturing systems, acid-stimulation systems, and flow control equipment and other systems.
Although the terms “ball seat” and “ball” are used herein, it is to be understood that a drop plug or other shaped plugging device or element may be used with the “ball seats” disclosed and discussed herein. For simplicity it is to be understood that the terms “ball” and “plug element” include and encompass all shapes and sizes of plugs, balls, darts, or drop plugs unless the specific shape or design of the “ball” is expressly discussed.
Stimulating, which as used herein includes fracturing or “fracing,” a wellbore using stimulation systems or tools also are known in the art. In general, stimulating systems or tools are used in oil and gas wells for completing and increasing the production rate from the well. In deviated wellbores, particularly those having longer lengths, fluid, such as acid or fracturing fluids, can be expected to be introduced into the linear, or horizontal, end portion of the well to stimulate the production zone to open up production fissures and pores there-through. For example, hydraulic fracturing is a method of using pump rate and hydraulic pressure created by fracturing fluids to fracture or crack a subterranean formation, or the wellbore environment.
Prior to stimulating a wellbore, a stimulation tool is cemented into the wellbore. Thereafter, a pressure test of the wellbore casing containing the stimulation tool is performed. To perform this step, the pathway through the stimulation tool must be closed off. After the casing test establishes the integrity of the wellbore casing, fluid communication of the pathway through the stimulation tool is reestablished so that the stimulation fluid can be pumped down through the stimulation tool and into the formation. Currently, the steps involved in reestablishing fluid flow through the stimulation tool require additional wellbore intervention such as by using tubing conveyed perforation.